U.S. patent application number 12/462638 was filed with the patent office on 2011-03-17 for composition and method for polishing bulk silicon.
Invention is credited to John Clark, Jeffrey Gilliland, Lamon Jones, Brian Reiss, Michael White.
Application Number | 20110062376 12/462638 |
Document ID | / |
Family ID | 43729582 |
Filed Date | 2011-03-17 |
United States Patent
Application |
20110062376 |
Kind Code |
A1 |
Reiss; Brian ; et
al. |
March 17, 2011 |
Composition and method for polishing bulk silicon
Abstract
The invention provides a polishing composition comprising (a)
silica, (b) one or more compounds that increases the removal rate
of silicon, (c) one or more tetraalkylammonium salts, and (d)
water, wherein the polishing composition has a pH of about 7 to
about 11. The invention further provides a method of polishing a
substrate with the polishing composition.
Inventors: |
Reiss; Brian; (Woodridge,
IL) ; Clark; John; (Montgomery, IL) ; Jones;
Lamon; (Aurora, IL) ; Gilliland; Jeffrey;
(Montgomery, IL) ; White; Michael; (Oswego,
IL) |
Family ID: |
43729582 |
Appl. No.: |
12/462638 |
Filed: |
September 16, 2009 |
Current U.S.
Class: |
252/79.5 ;
252/79.1 |
Current CPC
Class: |
H01L 21/02024 20130101;
C09K 3/1463 20130101; C09G 1/02 20130101 |
Class at
Publication: |
252/79.5 ;
252/79.1 |
International
Class: |
C09K 13/02 20060101
C09K013/02; C09K 13/00 20060101 C09K013/00 |
Claims
1. A chemical-mechanical polishing composition consisting
essentially of: (a) about 0.5 wt. % to about 20 wt. % of silica,
(b) about 0.02 wt. % to about 5 wt. % of one or more organic
carboxylic acids, (c) about 0.05 wt. % to about 2 wt. % of one or
more aminophosphonic acids, (d) about 0.1 wt. % to about 5 wt. % of
one or more tetraalkylammonium salts, (e) optionally one or more
bicarbonate salts, (f) optionally potassium hydroxide, and (g)
water, wherein the polishing composition has a pH of about 7 to
about 11.
2. The polishing composition of claim 1, wherein the polishing
composition contains about 5 wt. % to about 20 wt. % of silica.
3. The polishing composition of claim 2, wherein the polishing
composition contains about 10 wt. % to about 15 wt. % of
silica.
4. The polishing composition of claim 1, wherein the silica is
wet-process silica.
5. The polishing composition of claim 1, wherein the silica is
fumed silica.
6. The polishing composition of claim 1, wherein the polishing
composition contains about 0.1 wt. % to about 2 wt. % of the
organic carboxylic acid.
7. The polishing composition of any of claim 1, wherein at least
one organic carboxylic acid is a hydroxycarboxylic acid.
8. The polishing composition of claim 7, wherein the organic
carboxylic acid is an aliphatic hydroxycarboxylic acid.
9. The polishing composition of claim 8, wherein the organic
carboxylic acid is selected from the group consisting of lactic
acid, 2-hydroxybutyric acid, benzilic acid, and combinations
thereof.
10. The polishing composition of claim 1, wherein at least one
organic carboxylic acid is a hydroxybenzoic acid.
11. The polishing composition of claim 10, wherein the organic
carboxylic acid is selected from the group consisting of salicylic
acid, 2,6-dihydroxybenzoic acid, and combinations thereof.
12. The polishing composition of claim 10, wherein the organic
carboxylic acid is an amino hydroxybenzoic acid.
13. The polishing composition of claim 1, wherein at least one
carboxylic acid is an amino acid.
14. The polishing composition of claim 13, wherein the amino acid
is selected from the group consisting of proline, glycine, alanine,
and combinations thereof.
15. The polishing composition of any of claim 1, wherein the
polishing composition contains about 0.1 wt. % to about 1 wt. % of
at least one aminophosphonic acid.
16. The polishing composition of claim 15, wherein the
aminophosphonic acid is selected from the group consisting of
ethylenediaminetetra(methylene phosphonic acid), amino
tri(methylene phosphonic acid), diethylenetriaminepenta(methylene
phosphonic acid), and combinations thereof.
17. The polishing composition of claim 16, wherein the
aminophosphonic acid is amino tri(methylene phosphonic acid).
18. The polishing composition of claim 1, wherein at least one
bicarbonate salt is present in the polishing composition, and
wherein the bicarbonate salt is potassium bicarbonate.
19. The polishing composition of claim 1, wherein potassium
hydroxide is present in the polishing composition.
20. The polishing composition of claim 1, wherein the polishing
composition has a pH of about 8 to about 10.
21. A chemical-mechanical polishing composition consisting
essentially of: (a) about 0.5 wt. % to about 20 wt. % of silica,
(b) about 0.1 wt. % to about 2 wt. % of one or more
polyaminocarboxylic acids, (c) about 0.1 wt. % to about 5 wt. % of
one or more amines, (d) about 0.1 wt. % to about 5 wt. % of one or,
more tetraalkylammonium salts, (e) about 0.001 wt. % to about 1 wt.
% of one or more 1,3-diol compound, (f) optionally one or more
bicarbonate salts, and (g) water, wherein the polishing composition
has a pH of about 7 to about 11.
22. The polishing composition of claim 21, wherein the polishing
composition contains about 5 wt. % to about 20 wt. % of silica.
23. The polishing composition of claim 21, wherein the polishing
composition contains about 10 wt. % to about 15 wt. % of
silica.
24. The polishing composition of claim 21, wherein the silica is
wet-process silica.
25. The polishing composition of claim 21, wherein the silica is
fumed silica.
26. The polishing composition of claim 21, wherein the polishing
composition contains about 0.1 wt. % to about 1 wt. % of the
polyaminocarboxylic acid.
27. The polishing composition of claim 21, wherein the
polyaminocarboxylic acid is selected from the group consisting of
ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic
acid, N-(hydroxyethyl)ethylenediaminetriacetic acid,
nitrilotriacetic acid, salts, thereof, and combinations
thereof.
28. The polishing composition of claim 27, wherein the
polyaminocarboxylic acid is ethylenediaminetetraacetic acid.
29. The polishing composition of claim 21, wherein the polishing
composition contains about 0.1 wt. % to about 2 wt. % of the
amine.
30. The polishing composition of claim 21, wherein the amine is
selected from the group consisting of piperazine,
1-(2-aminoethyl)piperazine, 2-methyl-1-aminoethanol,
(2-aminoethyl)aminoethanol, and combinations thereof.
31. The polishing composition of claim 21, wherein the 1,3-diol
compound is selected from the group consisting of 1,3-butanediol,
2,4-pentanediol, 2,4-hexanediol, and combinations thereof.
32. The polishing composition of claim 21, wherein at least one
bicarbonate salt is present in the polishing composition, and
wherein the bicarbonate salt is potassium bicarbonate.
33. The polishing composition of claim 21, wherein the polishing
composition has a pH of about 8 to about 10.
34. A chemical-mechanical polishing composition consisting
essentially of: (a) about 0.5 wt. % to about 20 wt. % of silica,
(b) about 0.1 wt. % to about 2 wt. % of one or more
polyaminocarboxylic acids, (c) about 0.1 wt. % to about 5 wt. % of
one or more tetraalkylammonium salts, (d) about 0.1 wt. % to about
5 wt. % of one or more organic carboxylic acids, (e) optionally
about 0.1 wt. % to about 5 wt. % of one or more amines, (f)
optionally one or more bicarbonate salts, and (g) water, wherein
the polishing composition has a pH of about 7 to about 11.
35. The polishing composition of claim 34, wherein the polishing
composition contains about 5 wt. % to about 20 wt. % of silica.
36. The polishing composition of claim 34, wherein the polishing
composition contains about 10 wt. % to about 15 wt. % of
silica.
37. The polishing composition of claim 34, wherein the silica is
wet-process silica.
38. The polishing composition of claim 34, wherein the silica is
fumed silica.
39. The polishing composition of claim 34, wherein the polishing
composition contains about 0.1 wt. % to about 1 wt. % of the
polyaminocarboxylic acid.
40. The polishing composition claim 34, wherein the
polyaminocarboxylic acid is selected from the group consisting of
ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic
acid, N-(hydroxyethyl)ethylenediaminetriacetic acid,
nitrilotriacetic acid, salts, thereof, and combinations
thereof.
41. The polishing composition of claim 40, wherein the
polyaminocarboxylic acid is ethylenediaminetetraacetic acid.
42. The polishing composition of claim 34, wherein the polishing
composition contains about 0.1 wt. % to about 2 wt. % of the
organic carboxylic acid.
43. The polishing composition of claim 34, wherein at least one
organic carboxylic acid is a dicarboxylic acid.
44. The polishing composition of claim 43, wherein the organic
carboxylic acid is oxalic acid or benzilic acid.
45. The polishing composition of claim 34, wherein the polishing
composition contains about 0.1 wt. % to about 2 wt. % of the
amine.
46. The polishing composition of claim 34, wherein the amine is
selected from the group consisting of piperazine,
1-(2-aminoethyl)piperazine, 2-methyl-1-aminoethanol,
(2-aminoethyl)aminoethanol, and combinations thereof.
47. The polishing composition of claim 34, wherein at least one
bicarbonate salt is present in the polishing composition, and
wherein the bicarbonate salt is potassium bicarbonate.
48. The polishing composition of claim 34, wherein the polishing
composition has a pH of about 8 to about 10.
49. A chemical-mechanical polishing composition consisting
essentially of: (a) about 0.5 wt. % to about 20 wt. % of silica,
(b) about 0.02 wt. % to about 5 wt. % of one or more
nitrogen-containing heterocyclic compounds, (c) about 0.05 wt. % to
about 2 wt. % of one or more aminophosphonic acids, (d) about 0.1
wt. % to about 5 wt. % of one or more tetraalkylammonium salts, (e)
optionally one or more bicarbonate salts, and (f) water, wherein
the polishing composition has a pH of about 7 to about 11.
50. The polishing composition of claim 49, wherein the polishing
composition contains about 5 wt. % to about 20 wt. % of silica.
51. The polishing composition of claim 50, wherein the polishing
composition contains about 10 wt. % to about 15 wt. % of
silica.
52. The polishing composition of claim 49, wherein the silica is
wet-process silica.
53. The polishing composition of claim 49, wherein the silica is
fumed silica.
54. The polishing composition of claim 49, wherein the polishing
composition contains about 0.1 wt. % to about 2 wt. % of the
nitrogen-containing heterocyclic compound.
55. The polishing composition of claim 49, wherein at least one
nitrogen-containing heterocyclic compound is a triazole.
56. The polishing composition of claim 55, wherein the
nitrogen-containing heterocyclic compound is an aminotriazole.
57. The polishing composition of claim 56, wherein the
aminotriazole is selected from the group consisting of
3-amino-1,2,4-triazole, 3-amino-1,2,4-triazole-5-carboxylic acid,
3-amino-5-mercapto-1,2,4-triazole, and
4-amino-5-hydrazino-1,2,4-triazole-3-thiol.
58. The polishing composition of claim 49, wherein at least one
nitrogen-containing heterocyclic compound is a thiazole.
59. The polishing composition of claim 58, wherein the thiazole is
selected from the group consisting of 2-amino-5-methylthiazole,
2-amino-thiazoleacetic acid, and thiazole.
60. The polishing composition of claim 49, wherein at least one
nitrogen-containing heterocyclic compound is a heterocyclic
N-oxide.
61. The polishing composition of claim 60, wherein the
nitrogen-containing heterocyclic compound is selected from the
group consisting of 2-hydroxypyridine-N-oxide,
4-methylmorpholine-N-oxide, and picolinic acid N-oxide.
62. The polishing composition of claim 49, wherein the polishing
composition contains about 0.1 wt. % to about 1 wt. % of at least
one aminophosphonic acid.
63. The polishing composition of claim 62, wherein the
aminophosphonic acid is selected from the group consisting of
ethylenediaminetetra(methylene phosphonic acid), amino
tri(methylene phosphonic acid), diethylenetriaminepenta(methylene
phosphonic acid), and combinations thereof.
64. The polishing composition of claim 63, wherein the
aminophosphonic acid is amino tri(methylene phosphonic acid).
65. The polishing composition of claim 49, wherein at least one
bicarbonate salt is present in the polishing composition, and
wherein the bicarbonate salt is potassium bicarbonate.
66. The polishing composition of claim 49, wherein the polishing
composition has a pH of about 8 to about 10.
Description
BACKGROUND OF THE INVENTION
[0001] Silicon wafers used in electronic devices are typically
prepared from a single crystal silicon ingot that is first sliced
into thin wafers using a diamond saw, lapped to improve flatness,
and etched to remove subsurface damage caused by lapping. The
silicon wafers are then typically polished in a two-step process to
remove nanotopography caused by etching and to achieve the desired
thickness before the wafers are acceptable for use in electronic
devices.
[0002] In the first polishing step, a high removal rate is
required, and ideally the nanotopography would not be worsened
during this step. Nanotopography is a parameter that measures the
front-surface topology of an area and is defined as the deviation
of a surface within a spatial wavelength of around 0.2 to 20 mm.
Nanotopography differs from surface flatness in that, for
nanotopography, the flatness of the wafer surface is measured
relative to the wafer surface itself, while for surface flatness,
the flatness of the wafer surface is measured relative to a flat
chuck used to hold the wafer. Thus, a wafer may have perfect
flatness, yet still have nanotopography. If a wafer has surface
irregularities on the front and back sides of the wafer, but the
front and back surfaces are parallel, the wafer has perfect
flatness. However, the same wafer will exhibit nanotopography.
Nanotopography bridges the gap between roughness and flatness in
the topology map of wafer surface irregularities in spatial
frequency.
[0003] Conventional polishing compositions for silicon wafers
exhibit high removal rates for silicon, but produce increased
nanotopography of the silicon wafers. The increased nanotopography
puts increased demands on the second, final polishing step to
produce silicon wafers suitable for further processing into
semiconductor substrates. Thus, there remains a need in the art for
improved polishing compositions for silicon wafers.
BRIEF SUMMARY OF THE INVENTION
[0004] The invention provides a polishing composition comprising
(a) silica, (b) a compound or compounds that increases the removal
rate of silicon, (c) a tetraalkylammonium salt, and (d) water,
wherein the polishing composition has a pH of about 7 to about
11.
[0005] A first embodiment of the inventive chemical-mechanical
polishing composition comprises a chemical mechanical polishing
composition consisting essentially of or consisting of (a) about
0.5 wt. % to about 20 wt. % of silica, (b) about 0.02 wt. % to
about 5 wt. % of one or more organic carboxylic acids, (c) about
0.02 wt. % to about 2 wt. % of one or more aminophosphonic acids,
(d) about 0.1 wt. % to about 5 wt. % of one or more
tetraalkylammonium salts, (e) optionally one or more bicarbonate
salts, (f) optionally potassium hydroxide, and (g) water, wherein
the polishing composition has a pH of about 7 to about 11.
[0006] A second embodiment of the inventive chemical-mechanical
polishing composition comprises a chemical mechanical polishing
composition consisting essentially of or consisting of (a) about
0.5 wt. % to about 20 wt. % of silica, (b) about 0.01 wt. % to
about 2 wt. % of one or more polyaminocarboxylic acids, (c) about
0.05 wt. % to about 5 wt. % of one or more amines, (d) about 0.1
wt. % to about 5 wt. % of one or more tetraalkylammonium salts, (e)
about 0.001 wt. % to about 1 wt. % of one or more diol compounds,
(f) optionally one or more bicarbonate salts, and (g) water,
wherein the polishing composition has a pH of about 7 to about
11.
[0007] A third embodiment of the inventive chemical-mechanical
polishing composition comprises a chemical mechanical polishing
composition consisting essentially of or consisting of (a) about
0.5 wt. % to about 20 wt. % of silica, (b) about 0.01 wt. % to
about 2 wt. % of one or more polyaminocarboxylic acids, (c) about
0.1 wt. % to about 5 wt. % of one or more tetraalkylammonium salts,
(d) about 0.01 wt. % to about 5 wt. % of one or more organic
carboxylic acids, (e) optionally about 0.1 wt. % to about 5 wt. %
of one or more amines, (f) optionally one or more bicarbonate
salts, and (g) water, wherein the polishing composition has a pH of
about 7 to about 11.
[0008] A fourth embodiment of the inventive chemical-mechanical
polishing composition comprises a chemical mechanical polishing
composition consisting essentially of or consisting of (a) about
0.5 wt. % to about 20 wt. % of silica, (b) about 0.02 wt. % to
about 5 wt. % of one or more nitrogen-containing heterocyclic
compounds, (c) about 0.05 wt. % to about 2 wt. % of one or more
aminophosphonic acids, (d) about 0.1 wt. % to about 5 wt. % of one
or more tetraalkylammonium salts, (e) optionally one or more
bicarbonate salts, and (f) water, wherein the polishing composition
has a pH of about 7 to about 11.
[0009] The invention also provides a method for
chemically-mechanically polishing a substrate with the inventive
chemical-mechanical polishing composition.
[0010] A first embodiment of the inventive method for
chemically-mechanically polishing a substrate comprises (i)
contacting a substrate with a polishing pad and a chemical
mechanical polishing composition consisting essentially of or
consisting of (a) about 0.5 wt. % to about 20 wt. % of silica, (b)
about 0.02 wt. % to about 5 wt. % of one or more organic carboxylic
acids, (c) about 0.02 wt. % to about 2 wt. % of one or more
aminophosphonic acids, (d) about 0.1 wt. % to about 5 wt. % of one
or more tetraalkylammonium salts, (e) optionally one or more
bicarbonate salts, (f) optionally potassium hydroxide, and (g)
water, wherein the polishing composition has a pH of about 7 to
about 11, (ii) moving the polishing pad relative to the substrate
with the chemical-mechanical polishing composition therebetween,
and (iii) abrading at least a portion of the substrate to polish
the substrate.
[0011] A second embodiment of the inventive method for
chemically-mechanically polishing a substrate comprises (i)
contacting a substrate with a polishing pad and a chemical
mechanical polishing composition consisting essentially of or
consisting of (a) about 0.5 wt. % to about 20 wt. % of silica, (b)
about 0.01 wt. % to about 2 wt. % of one or more
polyaminocarboxylic acids, (c) about 0.05 wt. % to about 5 wt. % of
one or more amines, (d) about 0.1 wt. % to about 5 wt. % of one or
more tetraalkylammonium salts, (e) about 0.001 wt. % to about 1 wt.
% of one or more diol compounds, (f) optionally one or more
bicarbonate salts, and (g) water, wherein the polishing composition
has a pH of about 7 to about 11, (ii) moving the polishing pad
relative to the substrate with the chemical-mechanical polishing
composition therebetween, and (iii) abrading at least a portion of
the substrate to polish the substrate.
[0012] A third embodiment of the inventive method for
chemically-mechanically polishing a substrate comprises (i)
contacting a substrate with a polishing pad and a chemical
mechanical polishing composition consisting essentially of or
consisting of (a) about 0.5 wt. % to about 20 wt. % of silica, (b)
about 0.01 wt. % to about 2 wt. % of one or more
polyaminocarboxylic acids, (c) about 0.1 wt. % to about 5 wt. % of
one or more tetraalkylammonium salts, (d) about 0.01 wt. % to about
5 wt. % of one or more organic carboxylic acids, (e) optionally
about 0.1 wt. % to about 5 wt. % of one or more amines, (f)
optionally one or more bicarbonate salts, and (g) water, wherein
the polishing composition has a pH of about 7 to about 11, (ii)
moving the polishing pad relative to the substrate with the
chemical-mechanical polishing composition therebetween, and (iii)
abrading at least a portion of the substrate to polish the
substrate.
[0013] A fourth embodiment of the inventive method for
chemically-mechanically polishing a substrate comprises (i)
contacting a substrate with a polishing pad and a chemical
mechanical polishing composition consisting essentially of or
consisting of (a) about 0.5 wt. % to about 20 wt. % of silica, (b)
about 0.02 wt. % to about 5 wt. % of one or more
nitrogen-containing heterocyclic compounds, (c) about 0.05 wt. % to
about 2 wt. % of one or more aminophosphonic acids, (d) about 0.1
wt. % to about 5 wt. % of one or more tetraalkylammonium salts, (e)
optionally one or more bicarbonate salts, and (f) water, wherein
the polishing composition has a pH of about 7 to about 11, (ii)
moving the polishing pad relative to the substrate with the
chemical-mechanical polishing composition therebetween, and (iii)
abrading at least a portion of the substrate to polish the
substrate.
BRIEF DESCRIPTION OF THE DRAWING(S)
[0014] The FIGURE is a schematic drawing that illustrates the
surface parameter R.sub.max.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The invention provides a polishing composition comprising
(a) silica, (b) a compound or compounds that increases the removal
rate of silicon, (c) a tetraalkylammonium salt, and (d) water,
wherein the polishing composition has a pH of about 7 to about
11.
[0016] The silica can be any suitable form of silica such as
wet-process type silica, fumed silica, or combinations thereof. For
example, the silica can comprise wet-process type silica particles
(e.g., condensation-polymerized or precipitated silica particles).
Condensation-polymerized silica particles typically are prepared by
condensing Si(OH).sub.4 to form colloidal particles, where
colloidal particles are defined as having an average particle size
between about 1 nm and about 1000 nm. Such abrasive particles can
be prepared in accordance with U.S. Pat. No. 5,230,833 or can be
obtained as any of various commercially available products, such as
the Akzo-Nobel Bindzil 50/80 product, the Nalco DVSTS006 product,
and the Fuso PL-2 product, as well as other similar products
available from DuPont, Bayer, Applied Research, Nissan Chemical,
and Clariant.
[0017] The silica can comprise fumed silica particles. Fumed silica
particles can be produced from volatile precursors (e.g., silicon
halides) in a pyrogenic process by hydrolysis and/or oxidation of
the precursors in a high temperature flame (H.sub.2/air or
H.sub.2/CH.sub.4/air) to produce the fumed silica. The solution
containing the precursor can be sprayed into a high temperature
flame using a droplet generator, and the metal oxide can then be
collected. Typical droplet generators include bi-fluid atomizers,
high-pressure spray nozzles, and ultrasonic atomizers. Suitable
fumed silica products are commercially available from producers
such as Cabot, Tokuyama, and Degussa.
[0018] The silica can have any suitable average particle size
(i.e., average particle diameter). The silica can have an average
particle size of about 10 nm or more, e.g., about 15 nm or more,
about 20 nm or more, or about 25 nm or more. Alternatively, or in
addition, the silica can have an average particle size of about 120
nm or less, e.g., about 110 nm or less, about 100 nm or less, about
90 nm or less, about 80 nm or less, about 70 nm or less, about 60
nm or less, 50 nm or less, or about 40 nm or less. Thus, the silica
can have an average particle size bounded by any two of the above
endpoints. For example, the silica can have an average particle
size of about 10 nm to about 100 nm, about 20 nm to about 100 nm,
about 20 nm to about 80 nm, about 20 nm to about 60 nm, or about 20
nm to about 40 nm. For a non-spherical silica particle, the size of
the particle is the diameter of the smallest sphere that
encompasses the particle.
[0019] The polishing composition can comprise any suitable amount
of silica. Typically, the polishing composition can contain about
0.5 wt. % or more, e.g., about 1 wt. % or more, about 2 wt. % or
more, or about 5 wt. % or more of silica. Alternatively, or in
addition, the polishing composition can contain about 20 wt. % or
less, e.g., about 15 wt. % or less, about 10 wt. % or less, about 8
wt. % or less, about 6 wt. % or less, or about 5 wt. % or less of
silica. Thus, the polishing composition can comprise silica in an
amount bounded by any two of the above endpoints recited for
silica. For example the polishing composition can comprise about
0.5 wt. % to about 20 wt. %, about 1 wt. % to about 15 wt. %, about
5 wt. % to about 15 wt. %, or about 0.5 wt. % to about 5 wt. % of
silica.
[0020] The silica particles preferably are colloidally stable. The
term colloid refers to the suspension of silica particles in the
liquid carrier. Colloidal stability refers to the maintenance of
that suspension through time. In the context of this invention, an
abrasive is considered colloidally stable if, when the abrasive is
placed into a 100 ml graduated cylinder and allowed to stand
unagitated for a time of 2 hours, the difference between the
concentration of particles in the bottom 50 ml of the graduated
cylinder ([B] in terms of g/ml) and the concentration of particles
in the top 50 ml of the graduated cylinder ([T] in terms of g/ml)
divided by the initial concentration of particles in the abrasive
composition ([C] in terms of g/ml) is less than or equal to 0.5
(i.e., {[B]-[T]}/[C].ltoreq.0.5). More preferably, the value of
[B]-[T]/[C] is less than or equal to 0.3, and most preferably is
less than or equal to 0.1.
[0021] The polishing composition comprises water. The water is used
to facilitate the application of the abrasive particles,
compound(s) that increase the removal rate of silicon, and any
other additives to the surface of a suitable substrate to be
polished or planarized. Preferably, the water is deionized
water.
[0022] The polishing composition has a pH of about 11 or less
(e.g., about 10 or less). Preferably, the polishing composition has
a pH of about 7 or more (e.g., about 8 or more). Even more
preferably, the polishing composition has a pH of about 7 to about
11 (e.g., about 8 to about 10). The polishing composition
optionally contains pH adjusting agents, for example, potassium
hydroxide, ammonium hydroxide, and/or nitric acid. The polishing
composition also optionally comprises pH buffering systems. Many
such pH buffering systems are well known in the art. The pH
buffering agent can be any suitable buffering agent, for example,
bicarbonate-carbonate buffer systems, aminoalkylsulfonic acids, and
the like. The polishing composition can comprise any suitable
amount of a pH adjustor and/or a pH buffering agent, provided that
a suitable amount is used to achieve and/or maintain the pH of the
polishing composition within a suitable range.
[0023] A first embodiment of the inventive chemical-mechanical
polishing composition provides a chemical mechanical polishing
composition consisting essentially of or consisting of (a) about
0.5 wt. % to about 20 wt. % of silica, (b) about 0.02 wt. % to
about 5 wt. % of an organic carboxylic acid, (c) about 0.02 wt. %
to about 2 wt. % of an aminophosphonic acid, (d) about 0.1 wt. % to
about 5 wt. % of a tetraalkylammonium salt, (e) optionally a
bicarbonate salt, (f) optionally potassium hydroxide, and (g)
water, wherein the polishing composition has a pH of about 7 to
about 11.
[0024] The polishing composition of the first embodiment contains
one or more suitable organic carboxylic acids or salts thereof. The
organic carboxylic acid can be an alkyl carboxylic acid or aryl
carboxylic acid and can be optionally substituted with groups
selected from the group consisting of C.sub.1-C.sub.12 alkyl,
amino, substituted amino (e.g., methylamino, dimethylamino, and the
like), hydroxyl, halogen, and combinations thereof. Preferably, the
organic carboxylic acid is a hydroxycarboxylic acid (e.g., an
aliphatic hydroxycarboxylic acid or a hydroxybenzoic acid), an
amino acid, an amino hydroxybenzoic acid, or a pyridine carboxylic
acid. Non-limiting examples of suitable hydroxycarboxylic acids
include malonic acid, lactic acid, malic acid, tartaric acid,
acetohydroxamic acid, glycolic acid, 2-hydroxybutyric acid,
benzilic acid, salicylic acid, and 2,6-dihydroxybenzoic acid.
Non-limiting examples of suitable amino acids include glycine,
alanine, proline, lysine, cysteine, leucine, aspartic acid,
glutamic acid, and 2-amino-4-thiazolacetic acid. Non-limiting
examples of an amino hydroxybenzoic acid include 3-aminosalicylic
acid and 3-amino-4-hydroxybenzoic acid. Non-limiting examples of
pyridine carboxylic acids include picolinic acid and nicotinic
acid.
[0025] The polishing composition of the first embodiment can
contain any suitable amount of the organic carboxylic acid(s). The
polishing composition can contain about 0.02 wt. % or more, e.g.,
about 0.05 wt. % or more, about 0.1 wt. % or more, or about 0.5 wt.
% or more of the organic carboxylic acid(s). Alternatively, or in
addition, the polishing composition can contain about 5 wt. % or
less, e.g., about 4 wt. % or less, about 3 wt. % or less, about 2
wt. % or less, or about 1 wt. % or less of the organic carboxylic
acid(s). Thus, the polishing composition can comprise the organic
carboxylic acid(s) in an amount bounded by any two of the above
endpoints recited for the organic carboxylic acid(s). For example
the polishing composition can comprise about 0.02 wt. % to about 5
wt. %, 0.05 wt. % to about 4 wt. %, or about 0.1 wt. % to about 3
wt. % of the organic carboxylic acid(s).
[0026] The polishing composition of the first embodiment contains
one or more suitable aminophosphonic acids. Preferably, the
aminophosphonic acid is selected from the group consisting of
ethylenediaminetetra(methylene phosphonic acid), amino
tri(methylene phosphonic acid), diethylenetriaminepenta(methylene
phosphonic acid), salts thereof, and combinations thereof. More
preferably, the aminophosphonic acid is amino tri(methylene
phosphonic acid).
[0027] The polishing composition of the first embodiment can
contain any suitable amount of the aminophosphonic acid(s).
Typically, the polishing composition can contain about 0.02 wt. %
or more, e.g., about 0.1 wt. % or more, about 0.2 wt. % or more, or
about 0.5 wt. % or more of the aminophosphonic acid(s).
Alternatively, or in addition, the polishing composition can
contain about 2 wt. % or less, e.g., about 1.5 wt. % or less, or
about 1 wt. % or less of the aminophosphonic acid(s). Thus, the
polishing composition can comprise the aminophosphonic acid(s) in
an amount bounded by any two of the above endpoints recited for the
aminophosphonic acid(s). For example the polishing composition can
comprise about 0.02 wt. % to about 2 wt. %, 0.1 wt. % to about 1.5
wt. %, or about 0.5 wt. % to about 1 wt. % of the aminophosphonic
acid(s).
[0028] The polishing composition of the first embodiment comprises
one or more suitable tetraalkylammonium salt(s). The
tetraalkylammonium salt preferably comprises a cation selected from
the group consisting of tetramethylammonium, tetraethylammonium,
tetrapropylammonium, and tetrabutylammonium. The tetraalkylammonium
salt can have any suitable cation including but not limited to
hydroxide, chloride, bromide, sulfate, or hydrogensulfate. In an
embodiment, the tetraalkylammonium salt is a tetraalkylammonium
hydroxide (e.g., tetramethylammonium hydroxide).
[0029] The polishing composition of the first embodiment can
comprise any suitable amount of the tetraalkylammonium salt(s).
Typically, the polishing composition can contain about 0.1 wt. % or
more, e.g., about 0.1 wt. % or more, about 0.2 wt. % or more, or
about 0.5 wt. % or more of the tetraalkylammonium salt(s).
Alternatively, or in addition, the polishing composition can
contain about 5 wt. % or less, e.g., about 4 wt. % or less, about 3
wt. % or less, about 2 wt. % or less, or about 1 wt. % or less of
the tetraalkylammonium salt(s). Thus, the polishing composition can
comprise the tetraalkylammonium salt(s) in an amount bounded by any
two of the above endpoints recited for the tetraalkylammonium
salt(s). For example the polishing composition can comprise about
0.1 wt. % to about 5 wt. %, 0.2 wt. % to about 4 wt. %, or about
0.5 wt. % to about 3 wt. % of the tetraalkylammonium salt(s).
[0030] A second embodiment of the inventive chemical-mechanical
polishing composition provides a chemical mechanical polishing
composition consisting essentially of or consisting of (a) about
0.5 wt. % to about 20 wt. % of silica, (b) about 0.01 wt. % to
about 2 wt. % of a polyaminocarboxylic acid, (c) about 0.1 wt. % to
about 5 wt. % of an amine, (d) about 0.1 wt. % to about 5 wt. % of
a tetraalkylammonium salt, (e) about 0.001 wt. % to about 1 wt. %
of a diol compound, (f) optionally a bicarbonate salt, and (g)
water, wherein the polishing composition has a pH of about 7 to
about 11.
[0031] The polishing composition of the second embodiment comprises
one or more suitable polyaminocarboxylic acids. The term
polyaminocarboxylic acid as used herein refers to a compound having
two or more amino groups and two or more carboxylic acid groups.
Preferably, the polyaminocarboxylic acid is selected from the group
consisting of ethylenediaminetetraacetic acid,
diethylenetriaminepentaacetic acid,
N-(hydroxyethyl)ethylenediaminetriacetic acid, nitrilotriacetic
acid, methylglycinediacetic acid, salts thereof, and combinations
thereof. More preferably, the polyaminocarboxylic acid is selected
from the group consisting of ethylenediaminetetraacetic acid or a
salt thereof (e.g., a mono-, di-, tri-, or tetrasodium salt
thereof).
[0032] The polishing composition of the second embodiment can
comprise any suitable amount of the polyaminocarboxylic acid(s).
Typically, the polishing composition can contain about 0.01 wt. %
or more, e.g., about 0.1 wt. % or more, about 0.2 wt. % or more, or
about 0.5 wt. % or more of the polyaminocarboxylic acid(s).
Alternatively, or in addition, the polishing composition can
contain about 2 wt. % or less, e.g., about 1.5 wt. % or less, or
about 1.0 wt. % or less of the polyaminocarboxylic acid(s). Thus,
the polishing composition can comprise the polyaminocarboxylic
acid(s) in an amount bounded by any two of the above endpoints
recited for the polyaminocarboxylic acid(s). For example the
polishing composition can comprise about 0.01 wt. % to about 2 wt.
%, 0.1 wt. % to about 1.5 wt. %, or about 0.5 wt. % to about 1 wt.
% of the polyaminocarboxylic acid(s).
[0033] The polishing composition of the second embodiment comprises
one or more suitable amines. Non-limiting examples of suitable
amines include piperazine, aminoethylpiperazine,
2-methyl-2-aminoethanol, (2-aminoethyl)-2-aminoethanol,
ethanolamine, diethanolamine, triethanolamine, ethylenediamine,
diethylenetriamine, tetraethylenepentamine, hydrazine,
2-hydroxyethylhydrazine, semicarbazide, hydroxylamine,
N-methylhydroxylamine, O-methylhydroxylamine, and
O-carboxymethylhydroxylamine. More preferably, the amine is
piperazine or aminoethylpiperazine.
[0034] The polishing composition of the second embodiment can
comprise any suitable amount of the amine(s). Typically, the
polishing composition can contain about 0.05 wt. % or more, e.g.,
about 0.1 wt. % or more, about 0.2 wt. % or more, or about 0.5 wt.
% or more of the amine(s). Alternatively, or in addition, the
polishing composition can contain about 5 wt. % or less, e.g.,
about 4 wt. % or less, about 3 wt. % or less, about 2 wt. % or
less, or about 1 wt. % or less of the amine(s). Thus, the polishing
composition can comprise the amine(s) in an amount bounded by any
two of the above endpoints recited for the amine(s). For example
the polishing composition can comprise about 0.05 wt. % to about 5
wt. %, 0.2 wt. % to about 4 wt. %, or about 0.5 wt. % to about 3
wt. % of the amine(s).
[0035] The polishing composition of the second embodiment comprises
one or more suitable tetraalkylammonium salts. The
tetraalkylammonium salt and amount thereof can be as recited for
the first embodiment of the polishing composition.
[0036] The polishing composition of the second embodiment comprises
one or more suitable diol compounds. The diol compound can be any
suitable diol compound and typically is a 1,2-diol compound or a
1,3-diol compound. Typically, the diol compound is a linear or
branched-chain C.sub.2-C.sub.10 diol compound. Non-limiting
examples of suitable 1,2-diol compounds include 1,2-propane diol,
1,2-butane diol, 1,2-pentane diol, 2,3-pentane diol, and
combinations thereof. Non-limiting examples of suitable 1,3-diol
compounds include 1,3-propane diol, 1,3-butane diol, 1,3-pentane
diol, 2,4-pentane diol, and combinations thereof.
[0037] The polishing composition of the second embodiment can
comprise any suitable amount of the diol compound(s). Typically,
the polishing composition can contain about 0.001 wt. % or more,
e.g., about 0.005 wt. % or more, about 0.01 wt. % or more, or about
0.05 wt. % or more of the diol compound(s). Alternatively, or in
addition, the polishing composition can contain about 1 wt. % or
less, e.g., about 0.75 wt. % or less, about 0.5 wt. % or less,
about 0.25 wt. % or less, or about 0.1 wt. % or less of the diol
compound(s). Thus, the polishing composition can comprise the diol
compound(s) in an amount bounded by any two of the above endpoints
recited for the diol compound(s). For example the polishing
composition can comprise about 0.001 wt. % to about 1 wt. %, 0.005
wt. % to about 0.75 wt. %, or about 0.01 wt. % to about 0.5 wt. %
of the diol compound(s).
[0038] A third embodiment of the inventive chemical-mechanical
polishing composition comprises a chemical mechanical polishing
composition consisting essentially of or consisting of (a) about
0.5 wt. % to about 20 wt. % of silica, (b) about 0.01 wt. % to
about 2 wt. % of a polyaminocarboxylic acid, (c) about 0.1 wt. % to
about 5 wt. % of a tetraalkylammonium salt, (d) about 0.1 wt. % to
about 5 wt. % of an organic carboxylic acid, (e) optionally about
0.1 wt. % to about 5 wt. % of an amine, (f) optionally a
bicarbonate salt, and (g) water, wherein the polishing composition
has a pH of about 7 to about 11. The polyaminocarboxylic acid,
tetraalkylammonium salt, organic carboxylic acid, amine, and
amounts thereof contained in the third embodiment of the inventive
chemical-mechanical polishing composition can be as recited herein
for the first and second embodiments of the inventive polishing
composition.
[0039] A fourth embodiment of the inventive chemical-mechanical
polishing composition provides a chemical mechanical polishing
composition consisting essentially of or consisting of (a) about
0.5 wt. % to about 20 wt. % of silica, (b) about 0.02 wt. % to
about 5 wt. % of a nitrogen-containing heterocyclic compound, (c)
about 0.05 wt. % to about 2 wt. % of an aminophosphonic acid, (d)
about 0.1 wt. % to about 5 wt. % of a tetraalkylammonium salt, (e)
optionally a bicarbonate salt, and (f) water, wherein the polishing
composition has a pH of about 7 to about 11. The aminophosphonic
acid, tetraalkylammonium salt, and amounts thereof contained in the
fourth embodiment of the inventive chemical-mechanical polishing
composition can be as recited herein for the first embodiment of
the inventive polishing composition.
[0040] The polishing composition of the fourth embodiment comprises
one or more suitable nitrogen-containing heterocyclic compounds.
The term nitrogen-containing heterocyclic compound as used herein
refers to a 5-, 6-, or 7-membered ring compound having one or more
nitrogen atoms contained as part of the ring system. In an
embodiment, the nitrogen-containing heterocyclic compound is a
triazole. In a preferred embodiment, the nitrogen-containing
heterocyclic compound is an aminotriazole. Non-limiting examples of
suitable aminotriazoles include 3-amino-1,2,4-triazole,
3-amino-1,2,4-triazole-5-carboxylic acid,
3-amino-5-mercapto-1,2,4-triazole, and
4-amino-5-hydrazino-1,2,4-triazole-3-thiol. In another embodiment,
the nitrogen-containing heterocyclic compound is a thiazole.
Non-limiting examples of suitable thiazoles include
2-amino-5-methylthiazole, 2-amino-4-thoazoleacetic acid, and
thiazole. In another embodiment, the nitrogen-containing
heterocyclic compound is a heterocyclic N-oxide. Non-limiting
examples of suitable heterocyclic N-oxides include
2-hydroxypyridine-N-oxide, 4-methylmorpholine-N-oxide, and
picolinic acid N-oxide.
[0041] The polishing composition of the fourth embodiment can
comprise any suitable amount of the nitrogen-containing
heterocyclic compound. The polishing composition can contain about
0.02 wt. % or more, e.g., about 0.05 wt. % or more, about 0.1 wt. %
or more, or about 0.5 wt. % or more of the nitrogen-containing
heterocyclic compound(s). Alternatively, or in addition, the
polishing composition can contain about 5 wt. % or less, e.g.,
about 4 wt. % or less, about 3 wt. % or less, about 2 wt. % or
less, or about 1 wt. % or less of the nitrogen-containing
heterocyclic compound(s). Thus, the polishing composition can
comprise the nitrogen-containing heterocyclic compound(s) in an
amount bounded by any two of the above endpoints recited for the
nitrogen-containing heterocyclic compound(s). For example the
polishing composition can comprise about 0.02 wt. % to about 5 wt.
%, 0.05 wt. % to about 4 wt. %, or about 0.1 wt. % to about 3 wt. %
of the nitrogen-containing heterocyclic compound(s).
[0042] The polishing composition optionally further contains one or
more bicarbonate salts. The bicarbonate salt can be any suitable
bicarbonate salt and can be, for example, potassium bicarbonate,
sodium bicarbonate, ammonium bicarbonate, or combinations
thereof.
[0043] The polishing composition can contain any suitable amount of
the bicarbonate salt(s). Typically, the polishing composition can
contain about 0.05 wt. % or more, e.g., about 0.1 wt. % or more,
about 0.25 wt. % or more, or about 0.5 wt. % or more of the
bicarbonate salt(s). Alternatively, or in addition, the polishing
composition can contain about 5 wt. % or less, e.g., about 4 wt. %
or less, about 3 wt. % or less, about 2 wt. % or less, or about 1
wt. % or less of the bicarbonate salt(s). Thus, the polishing
composition can comprise the bicarbonate salt(s) in an amount
bounded by any two of the above endpoints recited for the
bicarbonate salt(s). For example the polishing composition can
comprise about 0.05 wt. % to about 1 wt. %, 0.1 wt. % to about 4
wt. %, about 0.25 wt. % to about 3 wt. %, or about 0.5 wt. % to
about 2 wt. % of the bicarbonate salt(s).
[0044] The polishing composition optionally further contains
potassium hydroxide. The polishing composition can contain any
suitable amount of potassium hydroxide. Typically, the polishing
composition can contain about 0.05 wt. % or more, e.g., about 0.1
wt. % or more, or about 0.25 wt. % or more of potassium hydroxide.
Alternatively, or in addition, the polishing composition can
contain about 2 wt. % or less, e.g., about 1.5 wt. % or less, about
1 wt. % or less, about 0.8 wt. % or less, or about 0.6 wt. % or
less of potassium hydroxide. Thus, the polishing composition can
comprise potassium hydroxide in an amount bounded by any two of the
above endpoints recited for potassium hydroxide. For example the
polishing composition can comprise about 0.05 wt. % to about 1 wt.
%, 0.1 wt. % to about 2 wt. %, about 0.1 wt. % to about 1 wt. %, or
about 0.25 wt. % to about 0.8 wt. % of potassium hydroxide.
[0045] The polishing composition optionally further comprises one
or more other additives. Such additives include any suitable
dispersing agent, such as, for example, homopolymers or random,
block, or gradient acrylate copolymers comprising one or more
acrylic monomers (e.g., polyacrylates, polymethacrylates, vinyl
acrylates and styrene acrylates), combinations thereof, and salts
thereof. Other suitable additives include biocides. The biocide can
be any suitable biocide, for example, an isothiazolinone
biocide.
[0046] The polishing composition of the invention can be prepared
by any suitable technique, many of which are known to those skilled
in the art. The polishing composition can be prepared in a batch or
continuous process. Generally, the polishing composition can be
prepared by combining the components thereof in any order. The term
"component" as used herein includes individual ingredients (e.g.,
silica, compound(s) that increases the removal rate of silicon,
tetraalkylammonium salt, etc.) as well as any combination of
ingredients (e.g., silica, compound(s) that increases the removal
rate of silicon, tetraalkylammonium salt, buffers, etc.).
[0047] For example, in one embodiment, the silica can be dispersed
in water. The organic carboxylic acid, aminophosphonic acid, and
tetraalkylammonium salt can then be added, and mixed by any method
that is capable of incorporating the components into the polishing
composition. Other compounds that increase the removal rate of
silicon similarly can be utilized in the preparation of the
polishing composition. The polishing composition can be prepared
prior to use, with one or more components, such as a pH adjusting
component, added to the polishing composition just before use
(e.g., within about 7 days before use, or within about 1 hour
before use, or within about 1 minute before use). The polishing
composition also can be prepared by mixing the components at the
surface of the substrate during the polishing operation.
[0048] The polishing composition also can be provided as a
concentrate which is intended to be diluted with an appropriate
amount of water prior to use. In such an embodiment, the polishing
composition concentrate can comprise, for example, silica, a
compound or compounds that increases the removal rate of silicon, a
tetraalkylammonium salt, and water in amounts such that, upon
dilution of the concentrate with an appropriate amount of water,
each component of the polishing composition will be present in the
polishing composition in an amount within the appropriate range
recited above for each component. For example, the abrasive,
compound or compounds that increases the removal rate of silicon,
and tetraalkylammonium salt can each be present in the concentrate
in an amount that is about 2 times (e.g., about 3 times, about 4
times, about 5 times, about 10 times, or about 15 times) greater
than the concentration recited above for each component so that,
when the concentrate is diluted with an equal volume of water
(e.g., 2 equal volumes water, 3 equal volumes of water, 4 equal
volumes of water, 9 equal volumes of water, or 14 equal volumes of
water, respectively), each component will be present in the
polishing composition in an amount within the ranges set forth
above for each component. Furthermore, as will be understood by
those of ordinary skill in the art, the concentrate can contain an
appropriate fraction of the water present in the final polishing
composition in order to ensure that the compound or compounds that
increases the removal rate of silicon, and other suitable additives
are at least partially or fully dissolved in the concentrate.
[0049] The invention further provides a method of
chemically-mechanically polishing a substrate comprising (i)
contacting a substrate with a polishing pad and the polishing
composition described herein, (ii) moving the polishing pad
relative to the substrate with the polishing composition
therebetween, and (iii) abrading at least a portion of the
substrate to polish the substrate.
[0050] Although the polishing composition of the invention can be
used to polish any substrate, the polishing composition is
particularly useful in the polishing of a substrate comprising
silicon, for example, silicon wafers used in the electronics
industry. In this regard, the silicon can be undoped silicon, or it
can be doped silicon, such as p-type silicon doped with boron or
aluminum. In addition, the silicon can be polysilicon. The
inventive polishing composition and method of use thereof is
suitable for the pre-polishing or the final polishing of silicon
wafers as produced from silicon single crystals by diamond sawing
and rough grinding, as well as for edge polishing of silicon wafers
and for use in the reclamation of silicon wafers by polishing.
[0051] Advantageously, the inventive polishing method exhibits
improves nanotopography when used to polish silicon wafers after
lapping and etching of diamond sawed silicon wafers. One way to
measure change in nanotopography during chemical-mechanical
polishing is to determine the value of the parameter:
.DELTA.R.sub.z/d wherein R.sub.z is the average maximum height of
the profile, .DELTA.R.sub.z is the change in % from one time point
to another time point, e.g., before and after chemical-mechanical
polishing, and d is the amount of material removed in microns over
that same time span, with the result expressed in nanometers.
Referring to the FIGURE, R.sub.max represents the largest peak to
valley height in a given sampling length L, and R.sub.z represents
the average of 5 R.sub.max values in 5 contiguous sampling lengths.
Sampling length L is approximately 5 mm. Suitable techniques for
measuring R.sub.max (to enable the calculation of %) include stylus
profilometry, optical profilometry, and atomic force microscopy.
Suitable instruments for stylus profilometry and optical
profilometry are available from, e.g., Veeco Instruments
(Plainview, N.Y.). Desirably, the inventive polishing method
results in a .DELTA.R.sub.z/d that is about zero or less, that is,
substrate nanotopography is either unchanged or improved after use
of the inventive polishing method.
[0052] The polishing method of the invention is particularly suited
for use in conjunction with a chemical-mechanical polishing
apparatus. Typically, the apparatus comprises a platen, which, when
in use, is in motion and has a velocity that results from orbital,
linear, or circular motion, a polishing pad in contact with the
platen and moving with the platen when in motion, and a carrier
that holds a substrate to be polished by contacting and moving the
substrate relative to the surface of the polishing pad. The
polishing of the substrate takes place by the substrate being
placed in contact with the polishing pad and the polishing
composition of the invention and then the polishing pad moving
relative to the substrate, so as to abrade at least a portion of
the substrate to polish the substrate.
[0053] A substrate can be polished with the chemical-mechanical
polishing composition with any suitable polishing pad (e.g.,
polishing surface). Suitable polishing pads include, for example,
woven and non-woven polishing pads. Moreover, suitable polishing
pads can comprise any suitable polymer of varying density,
hardness, thickness, compressibility, ability to rebound upon
compression, and compression modulus. Suitable polymers include,
for example, polyvinylchloride, polyvinylfluoride, nylon,
fluorocarbon, polycarbonate, polyester, polyacrylate, polyether,
polyethylene, polyamide, polyurethane, polystyrene, polypropylene,
coformed products thereof, and mixtures thereof. Hard polyurethane
polishing pads are particularly useful in conjunction with the
inventive polishing method.
[0054] Desirably, the chemical-mechanical polishing apparatus
further comprises an in situ polishing endpoint detection system,
many of which are known in the art. Techniques for inspecting and
monitoring the polishing process by analyzing light or other
radiation reflected from a surface of the substrate being polished
are known in the art. Such methods are described, for example, in
U.S. Pat. No. 5,196,353, U.S. Pat. No. 5,433,651, U.S. Pat. No.
5,609,511, U.S. Pat. No. 5,643,046, U.S. Pat. No. 5,658,183, U.S.
Pat. No. 5,730,642, U.S. Pat. No. 5,838,447, U.S. Pat. No.
5,872,633, U.S. Pat. No. 5,893,796, U.S. Pat. No. 5,949,927, and
U.S. Pat. No. 5,964,643. Desirably, the inspection or monitoring of
the progress of the polishing process with respect to a substrate
being polished enables the determination of the polishing
end-point, i.e., the determination of when to terminate the
polishing process with respect to a particular substrate.
[0055] The following examples further illustrate the invention but,
of course, should not be construed as in any way limiting its
scope.
Example 1
[0056] This example demonstrates the effect of an organic
carboxylic acid, an aminophosphonic acid, and a tetraalkylammonium
salt on the removal rate and surface roughness observed for silicon
substrates achievable by the polishing composition of the
invention.
[0057] Seven similar substrates, which substrates comprised 102 cm
(4 inch) diameter circular silicon wafers, were polished with seven
different polishing compositions (Polishing Compositions 1A-1G).
All of the polishing compositions contained 1 wt. % silica
wet-process silica (Polishing Compositions 1A, 1B, 1D, and 1F) or
fumed silica (Polishing Compositions 1C, 1E, and 1G), 0.27 wt. %
tetramethylammonium hydroxide, and 0.05 wt. % potassium bicarbonate
in water at a pH of about 10.5. Polishing Composition 1A
(comparative) further contained 0.017 wt. %
ethylenediaminetetraacetic acid and 0.067 wt. % piperazine.
Polishing Compositions 1B-1G further contained 0.033 wt. %
diethylenetriaminepenta(methylene phosphonic acid) and an organic
carboxylic acid, which was either 0.08 wt. % malonic acid
(Polishing Compositions 1B and 1C), 0.067 wt. % lactic acid
(Polishing Compositions 1D and 1E), or 0.107 wt. % malic acid
(Polishing Compositions 1F and 1G).
[0058] Following polishing, the removal rates for silicon and the
magnitude of the change in nanotopography, .DELTA.R.sub.z/d, were
determined for each of the polishing compositions. The results are
summarized in Table 1.
TABLE-US-00001 TABLE 1 Polishing Composition Silicon Removal Rate
(.ANG./min) .DELTA.R.sub.z/d (nm) 1A (comparative) 6500 6 1B
(invention) 5700 0 1C (invention) 5200 0.1 1D (invention) 5150 0.4
1E (invention) 5650 0.4 1F (invention) 5700 -0.2 1G (invention)
5400 0
[0059] As is apparent from the results set forth in Table 1, the
inventive polishing compositions exhibited silicon removal rates
that were approximately 79% to about 88% of the removal rate
exhibited by the comparative polishing composition, yet the
inventive polishing compositions exhibited a change in surface
roughness caused by polishing that ranged from a decrease in
surface roughness of approximately 0.2 nm (Polishing Composition
1F) to an increase in surface roughness of approximately 0.4 nm
(Polishing Compositions 1D and 1E), while the comparative polishing
composition exhibited an increase in surface roughness of
approximately 6 nm.
Example 2
[0060] This example demonstrates the effect of an organic
carboxylic acid, a polyaminocarboxylic acid, and a
tetraalkylammonium salt on the removal rate and surface roughness
observed for silicon substrates achievable by the polishing
composition of the invention.
[0061] Three similar substrates, which substrates comprised 102 cm
(4 inch) diameter circular silicon wafers, were polished with three
different polishing compositions (Polishing Compositions 2A-2C).
Polishing Composition 2A (comparative) contained 1 wt. %
wet-process silica, 0.0167 wt. % ethylenediaminetetraacetic acid,
0.067 wt. % piperazine, 0.27 wt. % tetramethylammonium hydroxide,
and 0.05 wt. % potassium bicarbonate. Polishing Composition 2B
(invention) contained 0.85 wt. % wet-process silica, 0.02 wt. %
ethylenediaminetetraacetic acid, 0.083 wt. % oxalic acid, 0.2 wt. %
tetramethylammonium hydroxide, and 0.1 wt. % potassium bicarbonate.
Polishing Composition 2C (invention) contained 0.53 wt. %
wet-process silica, 0.0167 wt. % ethylenediaminetetraacetic acid,
0.007 wt. % oxalic acid, 0.067 wt. % tetramethylammonium hydroxide,
and 0.05 wt. % potassium bicarbonate.
[0062] Following polishing, the removal rates for silicon and the
magnitude of the change in nanotopography, .DELTA.R.sub.z/d, were
determined for each of the polishing compositions. The results are
summarized in Table 2.
TABLE-US-00002 TABLE 2 Polishing Composition Silicon Removal Rate
(.ANG./min) .DELTA.R.sub.z/d (nm) 2A 6700 4 2B 5900 -4 2C 5500
-7
[0063] As is apparent from the results set forth in Table 2, the
inventive polishing compositions exhibited silicon removal rates
that were approximately 82% to about 88% of the removal rate
exhibited by the comparative polishing composition, yet the
inventive polishing compositions exhibited a decrease in surface
roughness caused by polishing of approximately 4 nm and 7 nm, as
compared to an increase in surface roughness caused by polishing
with the comparative polishing composition of approximately 4
nm.
Example 3
[0064] This example demonstrates the effect of an organic
carboxylic acid, a polyaminocarboxylic acid, an amine, and a
tetraalkylammonium salt on the removal rate and surface roughness
observed for silicon substrates achievable by the polishing
composition of the invention.
[0065] Two similar substrates, which substrates comprised 102 cm (4
inch) diameter circular silicon wafers, were polished with two
different polishing compositions (Polishing Compositions 3A and
3B). Polishing Compositions 3A and 3B contained 1 wt. % wet-process
silica, 0.0167 wt. % ethylenediaminetetraacetic acid, 0.067 wt. %
piperazine, 0.27 wt. % tetramethylammonium hydroxide, and 0.05 wt.
% potassium bicarbonate. Polishing Composition 3B (invention)
further contained 0.033 wt. % benzilic acid.
[0066] Following polishing, the removal rates for silicon and the
magnitude of the change in nanotopography, .DELTA.R.sub.z/d, were
determined for each of the polishing compositions. The results are
summarized in Table 2.
TABLE-US-00003 TABLE 3 Polishing Composition Silicon Removal Rate
(.ANG./min) .DELTA.R.sub.z/d (nm) 3A 6250 6 3B 2550 -6
[0067] As is apparent from the results set forth in Table 3, the
inventive polishing composition exhibited a silicon removal rate
that was approximately 42% of the removal rate exhibited by the
comparative polishing composition, yet the inventive polishing
composition exhibited a decrease in surface roughness caused by
polishing of approximately 6 nm as compared to an increase in
surface roughness caused by polishing with the comparative
polishing composition of approximately 6 nm.
Example 4
[0068] This example demonstrates the effect of a diol compound, a
polyaminocarboxylic acid, an amine, and a tetraalkylammonium salt
on the removal rate and surface roughness observed for silicon
substrates achievable by the polishing composition of the
invention.
[0069] Two similar substrates, which substrates comprised 102 cm (4
inch) diameter circular silicon wafers, were polished with two
different polishing compositions (Polishing Compositions 4A and
4B). Polishing Compositions 4A and 4B contained 1 wt. % wet-process
silica, 0.0167 wt. % ethylenediaminetetraacetic acid, 0.067 wt. %
piperazine, 0.27 wt. % tetramethylammonium hydroxide, and 0.05 wt.
% potassium bicarbonate. Polishing Composition 3B (invention)
further contained 0.033 wt. % 2,4-pentanediol (i.e., a diol
compound).
[0070] Following polishing, the removal rates for silicon and the
magnitude of the change in nanotopography, .DELTA.R.sub.z/d, were
determined for each of the polishing compositions. The results are
summarized in Table 4.
TABLE-US-00004 TABLE 4 Polishing Composition Silicon Removal Rate
(.ANG./min) .DELTA.R.sub.z/d (nm) 4A (comparative) 5350 -0.5 4B
(invention) 4375 -5
[0071] As is apparent from the results set forth in Table 4, the
inventive polishing composition exhibited a silicon removal rate
that was approximately 82% of the removal rate exhibited by the
comparative polishing composition, yet the inventive polishing
composition exhibited a decrease in surface roughness caused by
polishing of approximately 5 nm as compared to a decrease in
surface roughness caused by polishing with the comparative
polishing composition of approximately -0.5 nm.
[0072] All references, including publications, patent applications,
and patents, cited herein are hereby incorporated by reference to
the same extent as if each reference were individually and
specifically indicated to be incorporated by reference and were set
forth in its entirety herein.
[0073] The use of the terms "a" and "an" and "the" and similar
referents in the context of describing the invention (especially in
the context of the following claims) are to be construed to cover
both the singular and the plural, unless otherwise indicated herein
or clearly contradicted by context. The terms "comprising,"
"having," "including," and "containing" are to be construed as
open-ended terms (i.e., meaning "including, but not limited to,")
unless otherwise noted. Recitation of ranges of values herein are
merely intended to serve as a shorthand method of referring
individually to each separate value falling within the range,
unless otherwise indicated herein, and each separate value is
incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element as essential to the practice of
the invention.
[0074] Preferred embodiments of this invention are described
herein, including the best mode known to the inventors for carrying
out the invention. Variations of those preferred embodiments may
become apparent to those of ordinary skill in the art upon reading
the foregoing description. The inventors expect skilled artisans to
employ such variations as appropriate, and the inventors intend for
the invention to be practiced otherwise than as specifically
described herein. Accordingly, this invention includes all
modifications and equivalents of the subject matter recited in the
claims appended hereto as permitted by applicable law. Moreover,
any combination of the above-described elements in all possible
variations thereof is encompassed by the invention unless otherwise
indicated herein or otherwise clearly contradicted by context.
* * * * *